Background: Women with PCOS are hypothetically at higher risk for coronary heart disease (CHD) due to their increased incidence of obesity, dyslipidemia, hypertension and diabetes mellitus. Coronary artery calcification (CAC), a marker for coronary atherosclerosis, is detectable non-invasively by electron beam computed tomography (EBCT). This study determined the prevalence of subclinical CHD as determined by EBCT in a cohort of 30 - 45 year old premenopausal non-diabetic women with PCOS compared to ovulatory women. Methods: Each PCOS woman was matched to 2 ovulatory controls by age and body mass index (BMI). Local women (n=175 ) and men (n=154) who previously had undergone EBCT for the epidemiologic Rochester Family Heart Study served as additional historical community controls. Each subject had an EBCT scan and measurement of clinical CHD risk factors. A positive scan contained 1 or more calcified lesions, defined as 3/4 4 contiguous pixels exceeding 130 Hounsfield Units, within the coronary vessels. The Framingham Heart Study CHD risk prediction algorithms were used to calculate a CHD score for each subject.